Endoscopy is a minimally invasive medical procedure that allows a physician to interrogate the interior of the body through an endoscope, which provides a light source to illuminate the anatomy and a method for viewing the anatomy. Typically, the endoscope includes a set of fiber optic bundles connected to a viewing lens or a camera that provides video output. Examples of endoscopes include colonoscopes for examination and therapeutic use in the colon and bronchoscopes for the trachea and branching airways in the lungs. Such devices allow physicians to reach deep into the body through natural orifices, minimizing the trauma that would be required if more invasive procedures were performed.
Endoscopic procedures are often performed in conjunction with the analysis of medical images, either through the doctor's mental assessment or in computer-aided analysis of the images. Such image analysis is useful as the physician may be limited in their viewing ability by the endoscope, or to minimize procedure times by directing physicians to a certain diagnostic region of interest. Examples of medical images are those produced by fluoroscopy, computed tomography (CT), or magnetic resonance imaging. Such imaging allows the physician to discern parts of the anatomy that may not be viewable during the endoscopic procedure. For instance, in transthoracic needle biopsy, a needle is placed through a bronchoscope to sample the lymph nodes, which are located extraluminally, or beyond airway walls and thus out of the possibility of direct visualization. A CT scan is routinely used to determine the location of lymph nodes relative to the airways that are to be sampled. Such lymph node samples are important for the diagnosis and staging of lung cancer.
Imaging analysis is also useful to identify dimensions of anatomies such as the diameter of an airway. This information is useful in certain procedures such as, for example, determining a size of a tracheal bronchial stent to be in the trachea, or the size of an endotrachial valve to be placed in a segmental bronchial lumen. The determination, however, is complicated by a number of factors including the tidal motion of the lungs, i.e., inhalation and expiration of the lungs modifies the dimension of the lumens. Additionally, the dimension may vary along the length of the lumen.
Despite the availability of some of the known image analysis techniques, a method and system for obtaining the dimension information at a particular location in real time is desired.